Design of nanohybrids based on layered double hydroxides and electrochemically reduced graphene oxide for energy applications

Abstract

An innovative electrosynthesis method recently developed by our research group for the composite Ni/Al layered double hydroxide (LDH) intercalated with electrochemically reduced graphene oxide (ERGO) has been successfully applied to the deposition of Co/Al LDH ERGO on Grafoil sheets, demonstrating the high versatility of the procedure. Four materials have been electrosynthesized and characterized structurally and morphologically: Ni/Al LDH, Ni/Al LDH ERGO, Co/Al LDH, and Co/Al LDH ERGO. A deep investigation of their electrical and electrochemical properties in terms of Faradaic processes involving the redox active metal centers has been carried out. The effect of the presence of ERGO in the composite materials has been studied, highlighting an improvement of the electrical conductivity and the Faradaic process kinetics only for the Ni based LDH. The Co/Al LDH ERGO modified Grafoil was investigated as positive electrode in an asymmetric supercapacitor in solution and its performance compared with the one exhibited by the pure LDH. Also in such a case, the intercalation of ERGO inside the Co/Al LDH has not affected significantly its properties in terms of capacitance, but only has shown a positive effect on the material stability.